To evaluate the effect of initial concentrations on the adsorp- tion kinetics of MTBE onto the postcrosslinked polymer, the time courses of MTBE adsorption with different initial concentrations are presented in Fig. 6. Fitting results showed that the adsorption of MTBE with different initial concentrations followed pseudo- second-order kinetic model and the adsorption parameters are listed in Table 5. The adsorption rate constants were found to be3.07×10−4,2.95×10−4 and1.89×10−4gmg−1min−1 atMTBE initial concentrations of 26.5, 47.0 and 85.8mgl−1, respectively, indicating a decreased adsorption rate at higher initial concen- tration or MTBE adsorption amount. At low adsorption amounts, MTBE molecules tend to be quickly adsorbed into the open pores of polymeric adsorbents. At high adsorption amounts, however, MTBE molecules have to penetrate into the pores via a longer diffusion length, which eventually results in a decreased adsorption rate at high adsorption amount or initial concentration.
In well-stirred batch adsorption systems the intraparticle dif- fusion model has been used to describe the adsorption process